A New Look at Carbon Abundances in Planetary Nebulae. II. BB 1, NGC 650, NGC 1535, NGC 2440, and NGC 7027

Abstract

This paper is the second in a series that reports on the outcome of a study of carbon abundances in a carefully chosen sample of planetary nebulae representing a large range in progenitor mass and metallicity. We use the Final Archive lUE database containing consistently reduced lUE spectra to measure line strengths of C III] λ1909, along with numerous other UV lines for the planetary nebulae BB 1, NGC 650, NGC 1535, NGC 2440, and NGC 7027. Combining these measurements with optical data from the literature, we determine values for the abundance ratios He/H, 0/H, C/O, N/O, and Ne/O for these five objects using a five-level program, but we fine-tune the results with corrections derived from detailed photoionization models constrained by the same set of emission lines. All five objects show enhanced levels of C/O and N/O but depleted 0/H with respect to the Sun.